Diesel Versus Outboard
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dbsea
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I can't speak for everyone's boat, but i'm not sure my C-30 CB with the D6-435 is any more fuel efficient than the C32 with outboards. Granted I have a dinghy on the back acting like a drag parachute and a flybridge enclosure, but i'm not seeing much better than 17-18kn at 3000rpm and 1.2-1.3mpg. I think you can get the same or better with the dual outboards. Diesel fuel is incredibly expensive down here, i think its actually more expensive than premium gas right now in Seattle. 🙁
trailertrawlerkismet
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A boat manufacturer going from inboards to outboards, like model designs, are several years in the making. My guess this was set into place several years ago. I’ve had diesel inboards in our R27 and R29S and now have a Yamaha outboard on our R25 and can attest that the outboard gets just as good of fuel economy as the diesel, with the added benefit of being able to go fast. Is your question geared towards gas vs diesel or twin vs single outboard?
Jim F
Jim F
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+1 to Jim. IB vs OB seem to go back and forth on long cycles, according to overall market trends. Each has pro and con (like everything with boats).
There has been a lot of marketing emphasis lately on speed, which I suspect may be related to the influx of relatively new boaters. The C288 can achieve 45+ knots and cruise at 30, so a new boater might expect it to be like a car, "It can go 70 nm from Seattle to San Juans in 2 hours." (Reality is different, thanks to logs, traffic, & sea state!)
Personally I prefer inboard diesel but it's not right or wrong, just different optimization.
There has been a lot of marketing emphasis lately on speed, which I suspect may be related to the influx of relatively new boaters. The C288 can achieve 45+ knots and cruise at 30, so a new boater might expect it to be like a car, "It can go 70 nm from Seattle to San Juans in 2 hours." (Reality is different, thanks to logs, traffic, & sea state!)
Personally I prefer inboard diesel but it's not right or wrong, just different optimization.
pwensinger
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No one has mentioned safety. It takes alot to set off diesel, not much to turn those big gasoline tanks under the floor into bombs.
Also no one has mentioned availability. Owning a diesel boat requires more planning as to where to fill up. First, do they sell diesel, second, do they do enough volume so the fuel is fresh, not full of water and algae.
Also no one has mentioned availability. Owning a diesel boat requires more planning as to where to fill up. First, do they sell diesel, second, do they do enough volume so the fuel is fresh, not full of water and algae.
CruisingElvinRay
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Are you implying that Fluid Motion is making unsafe boats?pwensinger":2ruq8r8i said:
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BO-J
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It all comes down to give and take, and if you are going to own a boat, the last thing you should worry about is fuel cost. Between Moorage, insurance, normal upkeep, and repairs, fuel is the least of you worries.
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marob":1ykfbbyv said:
I'm sure the design of the C-288 has taken many years to come up with, while the fuel prices have risen greatly in the past year. Diesel is actually more expensive today at the fuel dock compared to gas. It's even worse than the fuel prices posted, since there's 31 cents per gallon in WA state to get a refund of the gas tax. (Diesel is usually dyed diesel at the fuel dock and is not eligible for a fuel tax refund).
I'm certainly not looking to start a "gas vs. diesel on a boat" debate. In all honesty, on a vehicle that gets between 1 and 4 mpg (gas or diesel), I really don't think it matters.
Fuel is one of the lesser expensive things that I spend on my boat. Boat payment, moorage, insurance, registration, maintenance, upgrades, guest moorage.... it all adds up. Without fuel, the boat is just a cold damp raft and not nearly as enjoyable.
I still work, so being able to burn 20gph is awful when I hit the fuel dock but gets me to my destination in a short amount of time. That time savings allows me to work from the boat more. I can't work on the boat while under way. But I can leave my dock in Everett at sunrise and be moored in Friday Harbor before my 9am meeting starts. To me, this is a big advantage of the outboards. It's the main reason I am able to use my boat so much. Also the ease of maintenance on the outboards for a DIY boater.
The outboards address customers like myself, who are destination boaters, where speed matters more than fuel costs, as well as the easier engine maintenance. But I also have options as I could drop the 9.9 kicker down, burn 1gph, and scoot along at 5 knots and enjoy the scenery.
I don't think FM or the rest of us had fuel economy in mind when they designed boats for today's market.
I was boating in 1974 when the OPEC oil embargo made it impossible to by gas for my daily job commute in Chicago. Everybody was swapping power boats for sailboats.....
The consumer today buys six dollar coffee and sixty dollar logo tee shirts....boating will carry on...
I was boating in 1974 when the OPEC oil embargo made it impossible to by gas for my daily job commute in Chicago. Everybody was swapping power boats for sailboats.....
The consumer today buys six dollar coffee and sixty dollar logo tee shirts....boating will carry on...
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SJI Sailor":2o083qbx said:
I've done Everett to Roche Harbor (65nm) in under 3 hours, many times.
Summer time, early morning, flat seas with clear visibility. Easy cruising. 🙂
scross
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Martin,
That’s usually a safer route to do at higher speed.
When you get to the Gulf Islands and Desolation Sound, the obstacles get much more frequent and substantial in nature. I’ve been in many long stretches of water up there where 7 knots is going way too fast to see and avoid. Sometimes it clear enough to go faster. We use to do 20 knots when safe in our previous boat. You just need to be able to completely shift gears, so to speak, as the dangers present themselves. It’s never exactly the same twice at the same place.
Don’t even get me started about the difficulties of dodging at speed around in a crowded crab pot field!
That’s usually a safer route to do at higher speed.
When you get to the Gulf Islands and Desolation Sound, the obstacles get much more frequent and substantial in nature. I’ve been in many long stretches of water up there where 7 knots is going way too fast to see and avoid. Sometimes it clear enough to go faster. We use to do 20 knots when safe in our previous boat. You just need to be able to completely shift gears, so to speak, as the dangers present themselves. It’s never exactly the same twice at the same place.
Don’t even get me started about the difficulties of dodging at speed around in a crowded crab pot field!
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My observation is that diesel engines used to be bulletproof and outboards were not as reliable, noisy and Smokey. Things seemed to have reversed. Once they added all the electronics to the diesels most issues have been electronic related. It seems to be harder now to find a good diesel mechanic also. Parts are easier to get for the outboards and working on them easier than working upside down in tight quarters. However, if I was on the water I would prefer the inboard to work on. Having had both I really have taken a liking to the new outboards.
Martin610
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I too wondered if FM has mis-read the market when they started going with gasoline outboards. There seem to be several factors in play.
It is cheaper to install outboards, thus maximizing profit for FM. I also think the influx of 'new' people to boating tend to gravitate to outboards. They are more familiar with them, like the extra speed, etc. They also think diesel engines have an odor and are noisy. More experienced boaters know that isn't generally true with newer diesel power plants. Some new boaters may not have the experience to realize that fuel economy is an issue.
I was at the Atlantic City boat show this year. A salesman was telling me that the new TrueNorth 38 with twin outboards got 3 1/2 to 4 miles a gallon at cruise. I just walked away. A new person without experience might not catch that.
Diesel engines are more fuel efficient for several reasons. Density of the fuel, thermal efficiency, are some of the factors. Here's one link on that but an internet search will many, many sources on this: https://www.bellperformance.com/blog/di ... it-for-you
Generally, sources quote efficiency gains of anywhere from 20% to 45%, I think 30% is most common.
After running Yamaha engines for fifteen years, personally, I would miss my bus heater, engine created hot water, easier dingy storage, and view from the stern. But that's me. Everyone has their own values.
However, the efficiency factor is always there. That's the reason commercial vehicles are over whelming diesel. I have noticed that vehicles like pickup trucks often debut new models with gasoline engines first. Later, diesel engines are brought out. FM may do something like that, and we might see a C-288 for example, with a diesel option. One C-24 was reportedly built as a diesel at the request of a customer.
That's boating. Always something interesting going on.
-martin610
It is cheaper to install outboards, thus maximizing profit for FM. I also think the influx of 'new' people to boating tend to gravitate to outboards. They are more familiar with them, like the extra speed, etc. They also think diesel engines have an odor and are noisy. More experienced boaters know that isn't generally true with newer diesel power plants. Some new boaters may not have the experience to realize that fuel economy is an issue.
I was at the Atlantic City boat show this year. A salesman was telling me that the new TrueNorth 38 with twin outboards got 3 1/2 to 4 miles a gallon at cruise. I just walked away. A new person without experience might not catch that.
Diesel engines are more fuel efficient for several reasons. Density of the fuel, thermal efficiency, are some of the factors. Here's one link on that but an internet search will many, many sources on this: https://www.bellperformance.com/blog/di ... it-for-you
Generally, sources quote efficiency gains of anywhere from 20% to 45%, I think 30% is most common.
After running Yamaha engines for fifteen years, personally, I would miss my bus heater, engine created hot water, easier dingy storage, and view from the stern. But that's me. Everyone has their own values.
However, the efficiency factor is always there. That's the reason commercial vehicles are over whelming diesel. I have noticed that vehicles like pickup trucks often debut new models with gasoline engines first. Later, diesel engines are brought out. FM may do something like that, and we might see a C-288 for example, with a diesel option. One C-24 was reportedly built as a diesel at the request of a customer.
That's boating. Always something interesting going on.
-martin610
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One other item is that having an outboard engine frees up storage space in the cockpit.
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I think the inboards match the style of Ranger Tug much better.
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This is an open discussion and all answers are right ??? Sort of !
Modern day diesels, Common rail, are fuel efficient, environmentally better than the older style mechanical diesels, weight to Hp ratio is much better because the displacement is smaller and HP is greater. Good fuel management and lots of turbo boost is the new way of power without displacement. What does all that mean? It means that the old iron horses that lasted 10,000 hours +, burning 2 gph at 50% load and making 120 hp at WOT are gone. The new diesels under 3L making over 220 Hp burning 6 gph at 50% load are here and lucky to get 3000 hours plus.
Modern day outboard 4 strokes are the same displacement as comparable hp modern day diesels. Fully electronic engine management same as the modern diesel. The dependability and longevity is remarkably about the same. The biggest differences is fuel type, diesel or gas.
Diesel by burns more efficiently making about 18 HP per gallon burned. Gas is about 12 hp per gallon burned. So about 1/3 more power per gallon. Gas right now is cheaper at the pump by 50 cents a gallon +/- so sometimes that makes a difference.
Ranger Tug and Cutwaters diesel or gas ? Which gets better fuel economy ? In my opinion neither. Trailerable boats have short water line lengths (LWL) which equates to slow hull speeds. What does that mean? If you have a 25' , 26' , 27 ' or 28 ' boat and you are cruising above 7kts your fuel economy is not going to be very good. Outboard (gas) or Diesel. My cutwater C26 D3 220hp AVERAGED (AVERAGE means just that! Best and worst averaged together! 4mpg at 6.5 kts 3mpg at 7kts, 2.5mpg at 8Kts 1.75 mpg anything above that 9kts to 20kts. I believe that the outboard engines will give similar fuel economy but capable of going faster.
My opinion of neither. A 35' to 40' diesel powered boat will average better fuel economy at 8kts compared to a 25' to 28' Ranger or Cutwater. Why? water line length (LWL). I own a twin engine diesel 34' that has a dry weight of 16000 lbs I get better fuel economy with it at 8kts than I did with my Cutwater C26. My fuel economy is the same at 14kts. 34' compared to 26' Cutwater . Anything above that I burn more but not as bad has I thought it would be 20 kts 17 gph =1.35 MPG, WOT = 23.5 KTS 26.5 gph = 1.1 mpg. My cutwater at best WOT 18.5KTS average 1.70 mpg not much different and the 34" is a lot more boat.
So what was Fluid Motion thinking when they changed from diesels to outboards. My opinion ! They are building trailerable boats. It doesn't matter if it is a Diesel or Outboard, the fuel economy is going to be the same. The boat will be faster and probably attract more new boaters to a different style of boating. The outboard style boat was viewed by many as a day cruiser. The Ranger and Cutwater boats can give you that plus a Swiss army knife interior that gives you long term cruising capability. Best of both worlds. The fuel economy with theses short LWL boats is made up when its on the trailer. My 34' doesn't tow well ! In fact to have it shipped right now to the PNW is about 20K. If I still had my C26 I would get 8 mpg towing it ,use about 300 gallons of fuel at $5.00 a gallon = 1500.00 in fuel to tow it!
So what was Fluid Motion thinking Diesel Verse Outboard ? Marketing , Marketing , Marketing ! Most boat manufactures are building outboard 4 stoke powered boats. They better do it to ! They did and it looks like it is working!
Modern day diesels, Common rail, are fuel efficient, environmentally better than the older style mechanical diesels, weight to Hp ratio is much better because the displacement is smaller and HP is greater. Good fuel management and lots of turbo boost is the new way of power without displacement. What does all that mean? It means that the old iron horses that lasted 10,000 hours +, burning 2 gph at 50% load and making 120 hp at WOT are gone. The new diesels under 3L making over 220 Hp burning 6 gph at 50% load are here and lucky to get 3000 hours plus.
Modern day outboard 4 strokes are the same displacement as comparable hp modern day diesels. Fully electronic engine management same as the modern diesel. The dependability and longevity is remarkably about the same. The biggest differences is fuel type, diesel or gas.
Diesel by burns more efficiently making about 18 HP per gallon burned. Gas is about 12 hp per gallon burned. So about 1/3 more power per gallon. Gas right now is cheaper at the pump by 50 cents a gallon +/- so sometimes that makes a difference.
Ranger Tug and Cutwaters diesel or gas ? Which gets better fuel economy ? In my opinion neither. Trailerable boats have short water line lengths (LWL) which equates to slow hull speeds. What does that mean? If you have a 25' , 26' , 27 ' or 28 ' boat and you are cruising above 7kts your fuel economy is not going to be very good. Outboard (gas) or Diesel. My cutwater C26 D3 220hp AVERAGED (AVERAGE means just that! Best and worst averaged together! 4mpg at 6.5 kts 3mpg at 7kts, 2.5mpg at 8Kts 1.75 mpg anything above that 9kts to 20kts. I believe that the outboard engines will give similar fuel economy but capable of going faster.
My opinion of neither. A 35' to 40' diesel powered boat will average better fuel economy at 8kts compared to a 25' to 28' Ranger or Cutwater. Why? water line length (LWL). I own a twin engine diesel 34' that has a dry weight of 16000 lbs I get better fuel economy with it at 8kts than I did with my Cutwater C26. My fuel economy is the same at 14kts. 34' compared to 26' Cutwater . Anything above that I burn more but not as bad has I thought it would be 20 kts 17 gph =1.35 MPG, WOT = 23.5 KTS 26.5 gph = 1.1 mpg. My cutwater at best WOT 18.5KTS average 1.70 mpg not much different and the 34" is a lot more boat.
So what was Fluid Motion thinking when they changed from diesels to outboards. My opinion ! They are building trailerable boats. It doesn't matter if it is a Diesel or Outboard, the fuel economy is going to be the same. The boat will be faster and probably attract more new boaters to a different style of boating. The outboard style boat was viewed by many as a day cruiser. The Ranger and Cutwater boats can give you that plus a Swiss army knife interior that gives you long term cruising capability. Best of both worlds. The fuel economy with theses short LWL boats is made up when its on the trailer. My 34' doesn't tow well ! In fact to have it shipped right now to the PNW is about 20K. If I still had my C26 I would get 8 mpg towing it ,use about 300 gallons of fuel at $5.00 a gallon = 1500.00 in fuel to tow it!
So what was Fluid Motion thinking Diesel Verse Outboard ? Marketing , Marketing , Marketing ! Most boat manufactures are building outboard 4 stoke powered boats. They better do it to ! They did and it looks like it is working!
CruisingElvinRay
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An important factor for us was maintenance. I spent enough time upside down maintaining my twin engine boat, and was super excited when the outboards were released. Plus, a re-power would be a one day job.
Also, one less hole in the boat and room to store our dinghy in the center locker of our R-23.
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Also, one less hole in the boat and room to store our dinghy in the center locker of our R-23.
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HawaiianFish
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Like Martin610 said I really appreciate hot water, easier dingy storage, and view from the stern not to mention the longevity of the Diesel engines. When buying boats this expensive, it’s nice to know your engine could last decades.
As far as speed, that is definitely a trade off, but 20knts cruise isn’t too shabby for my 14.5K lbs boat.
Honestly though, for my wife and I, it came down to having a clean stern and open feeling in the cockpit, and ease of working on and longevity of a modern diesel. We did love how quiet the outboards are though!
As far as speed, that is definitely a trade off, but 20knts cruise isn’t too shabby for my 14.5K lbs boat.
Honestly though, for my wife and I, it came down to having a clean stern and open feeling in the cockpit, and ease of working on and longevity of a modern diesel. We did love how quiet the outboards are though!
BB marine
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marob":3xbwesas said:
I believe this thread was geared more to fuel economy than what qualities we like better outboard or inboard. I'm posting some threads that deal with fuel economy of Gas powered 4 stroke outboards and the Volvo D3 to D6 diesel inboards.
sea trial of a 2015 C30 with the larger 435hp.
Empty boat for equipment.
AC/Generator.
Clean, but painted bottom.
160 gallons of fuel.
about 1/2 water.
5 adults.
calms seas no current.
Sea level in Florida.
After the fact: Propeller is fine, no damage. Engine makes max RPM. No smoke. Normal engine temps.
Fuel stats:
1400 rpm 1.6gph 6.8kts
1800 rpm 4.3gph 8kts
1900 rpm 5.1 gph 8.2kts
2800 rpm 14 gph 14kts
3000 rpm 15.8 gph 16kts
3000 rpm 16.0gph 16kts
3450 rpm 22 gph 20kts
3500 rpm wot 22.1 gph 21 kts
viewtopic.php?f=2&t=17591&start=15&hilit=cutwater+30+performance
This thread started to have traction and then went away. There is some information that gives a good base line as to the fuel economy comparison of diesel powered boats and two outboard powered boats a R27 and a Cutwater C302. This would be a good opportunity to start this back up now that there are more outboard models available. The ability to compare fuel and performance numbers between other Tugnuts is a good tool.
I will comment on the subject of longevity, Common rail high output diesel and an outboard four stroke. I believe if you look at how many newer designed 4 stoke outboards are being used in a commercial application and compare the hours to a common rail high output marine diesel engine. It is a wash if they are used at 50% load or higher. If you compare the larger Cutwater C30 to the C 302 inboard verse outboard ,based on a couple of Tugnuts posting. The C302 @ 4100 rpm is cruising at 26 mph or 22.5 kts , running just over 50% on both engines 26.6 gph = .97 mpg. The C30 435Hp @ 3450 rpm is cruising at 20kts running at just over 90% load, 22 gph = 1.04 mpg. The outboard is running 3 mph faster and real close to the same fuel economy. Because it is cruising faster it is clocking less hours in a 100 mile cruise. About a 1/2 hour less operation on a 100 mile trip, Trivial? Yes ! For someone that cruises a lot and is looking for years of longevity my bet is the Common Rail D6 or D4 longevity will not be any better than the Yamaha 4.2 L engines if operated in the higher load ranges. I believe the 4.2 L Yamaha will exceed the D3 Volvo in longevity. My opinion is the 2.8 L used on the R23 will equally have the same longevity.
My point is fuel economy and longevity are not real reasons for the choice of engines. The choice should be what suits your needs the best. Both the inboards and outboards Ranger Tugs will be great choices if this is the style boating you want. For me if I'm long distant cruising, Diesel Inboard is my choice. If I'm day or weekend cruising the outboard would be my choice. Why? If I'm long distant cruising I'm not cruising at 18 or 20 kts. My average speed will probably be 8 to 10 kts with an occasional go fast period of 14 to 18 kts. If I'm weekend cruising or day cruising I will be running at a faster clip to get where I want to go and spend the weekend.
So marop I don't think fuel prices even crossed fluid motions mind. There isn't that much difference. They are building for the market!